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[Java教程]如何为 setTimeout() 方法传参


现有如下JavaScript代码:

function printApple(apple){

  console.log(apple, "is a kind of healthy fruit");

}

var apple = "apple";

setTimeout("printApple(apple)", 5000);

则在执行setTimeout时,会报 apple is not defined,那么应该如何传参数呢?

1、 匿名函数

setTimeout(function(){

  console.log(apple, "is a kind of healthy fruit");

}, 5000);

2、Function.prototype.bind()

setTimeout(printApple.bind(null, apple), 5000);

3、第三个参数作为 setTimeout() 内部函数的参数,其实setTimeout()可以接受多个参数:setTimeout(yourFunctionReference, 5000, param1, param2, paramN);

var apple = "apple";

setTimeout(printApple, 5000, apple);

由于IE10以前的版本,不支持为setTimeout()和setInterval()方法传递第三个参数,所以在IE10以前的版本使用时,要添加以下代码:

if (document.all && !window.setTimeout.isPolyfill) { var __nativeST__ = window.setTimeout; window.setTimeout = function (vCallback, nDelay /*, argumentToPass1, argumentToPass2, etc. */) {  var aArgs = Array.prototype.slice.call(arguments, 2);  return __nativeST__(vCallback instanceof Function ? function () {   vCallback.apply(null, aArgs);  } : vCallback, nDelay); }; window.setTimeout.isPolyfill = true;}if (document.all && !window.setInterval.isPolyfill) { var __nativeSI__ = window.setInterval; window.setInterval = function (vCallback, nDelay /*, argumentToPass1, argumentToPass2, etc. */) {  var aArgs = Array.prototype.slice.call(arguments, 2);  return __nativeSI__(vCallback instanceof Function ? function () {   vCallback.apply(null, aArgs);  } : vCallback, nDelay); }; window.setInterval.isPolyfill = true;}

Any anonymous function will change "this" to point to window, so you will lose your object reference.